Electrical Engineering Department EE 400, Experiment # 4 IP Addressing and Subnetting

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1 Electrical Engineering Department EE 400, Experiment # 4 IP Addressing and Subnetting Objectives: After this experiment, the students should be able to configure for networking, assign IP address, and subnet mask to any of the host running on windows 98 OS. They should be able to test the connectivity of the host to the network and check the network status. IP addressing: Net ID First Host Last Host Net ID (bytes) Host ID (bytes) Class A 1 3 First Last Class B 2 2 First Last Class C 3 1 First Last Size of Net Huge # of Host, Less # of NW # of Host = # of NW Huge # f NW, Less # of Hosts 24

2 Class D: a multicast address. ( ) Class E: reserved for future use. ( ) Special forms of INTERNET Addresses For class C address, only 254 hosts can be supported because 0 is reserved for boot process 255 reserved for broadcast e.g This host. 0.host_number - host on this net Limited broadcast (local net). net_number Directed broadcast for the specified net. (e.g broadcast to all hosts of the local network.) 127.anything - Loop back (should never appear on the net). IP Subnetting Subnetting is a Technique used to allow a single IP network address to span multiple physical networks. IP hosts should support subnetting. Subnetting is done by using some of the bits of the host-id part of the IP address as a physical network identifier. The subnet mask is used to determine the bits of the network identifier. All hosts on the same network should have the same subnet mask. An example of Subnetting: The Class B network can be subnetted using the first 8 bits of the host-id, to span 254 different physical networks. The subnet mask for this case is The subnetworks are: , ,..., Each of the subnetworks can have up to 254 different hosts: XXX.1, XXX.2,..., XXX.254. If there is a need for less physical nets and more hosts in each one, less host-id bits can be used for subnetting. For example: With the subnet mask , 126 different subnets are available with up to 510 hosts in each one. Many Class A and B networks do not contain as many hosts as they could. This situation causes a lot of address space waste. Subnetting better utilizes the address space by dividing these big networks to smaller ones. IP Subnetting examples Class C subnetting example. In Host ID, 3 bits are used for subnet, 5 are used for Hosts Only (2 5 = 32) 2 = 30 Host are allowed for each subnet because 31 used for broadcast 0 used for bootup Only (2 3 = 8) 1 = 7 subnets are allowed because 25

3 0 is not allowed Subnet mask for Host ID field will be ( ) b = (224) d Thus full Subnet mask will be Class B subnetting example. Dividing a single Class B network into two subnetworks: Configuring the HOSTS File: You will add host name/ip address mappings to your HOSTS file, and then use the file to resolve host names. Pinging local hostname: You will ping the name of local host to verify that Microsoft TCP.IP can resolve local host names without entries in the HOSTS file. 1. Type ping hostname (where hostname is the name of your computer) and then press Enter. See what was the response? 2. Type ping hostname (where hostname is the name of another computer) and then press Enter. See what was the response? Pinging Remote hostname: 1. Type ping vlsi and then press Enter. (vlsi is the remote computer name). See what was the reponse? 26

4 Editing HOSTS File: 1. Start command prompt, and then change the directory to cd d:\winnt\system32\drivers\etc 2. You will now use a text editor to modify a file called HOSTS. Type edit hosts and then press Enter. 3. Add the following entry to the HOSTS file: vlsi 4. Press Alt key, then Save the file, and then Exit. Using HOSTS file for name resolution: 1. Type ping vlsi and then press Enter. See what was the response. Domain Name System (DNS) The Domain Name System protocol provides a mapping between cryptic IP address and, easier to remember, host names. Host names are used because they are easier for humans to remember. For example, telnet itc.itc.kfupm.edu.sa is easy to remember than telnet The Internet Domain Name System (DNS) is an attempt to decentralize administration of the mapping of host names to host addresses by the use of name-servers, each of which controls part of name space. This becomes necessary partly because the static host table formerly used for that purpose most of the hosts in the Internet are on networks local to particular organizations. It is desirable to allow the local administration to control that mapping. The DNS also implements a hierarchical naming scheme and provides protocols for communication with the name-servers. A set of top-level domains is administered by the Internet and is defined in the basic DNS specifications. Top Level Domains: The top level domains can be categorized as Organizational and Geographic: com edu gov mil net org XX Commercial Educational Governmental Military Administrative organizations for network such as CSNET, BITNET etc. Other Organizations two letter country code, e.g., sa for Saudi Arabia. DNS Naming Convention: Besides the root, each node in DNS database has a name of up to 63 characters. Each sub domain must have a unique name within its parent domain. Domains-Subtrees of the Entire Database: 27

5 Root-Level Domain: Top of the hierarchy is called the root domain. Top-Level Domain: First level domain contains second level domains and hosts. Top Level domains include.com and.net. This is a child of the root. Second-Level Domain: It contains hosts and other domains called subdomains. Microsoft.com and Compaq.com are second level domains. Second level domains are children of First-Level Domains. Third-Level Domain: It contains hosts and other domains called subdomains. mspress.microsoft.com is a subdomain and a third-level domain. A third-level domain is a child of a second-level domain. DNS Operation: DNS uses a client/server model, in which DNS servers (name servers) contain information about the DNS database and make this information available to clients (resolvers). DNS name servers perform name resolution by interpreting network information to find a specific IP address. Let see how DNS operates using the example of widget.universal.com 1. A resolver (or client) passes a query to its local name server. 2. The local name server sends an iterative request to one of the DNS root servers, requesting resolution of the domain name. The DNS root server returns a referral to the name servers that are authoritative for the com DNS domain. 3. The local name server sends an iterative request to one of the com name servers, which responds with a referral to the universal name servers. 4. The local name server sends an iterative request to one of the universal name servers. 5. When the universal name server receives the request from the local name server, it passes the widget piece of the DNS name to its local WINS server for resolution, WINS returns the IP address for widget to the universal name servers, which returns the IP address of the domain name to the local DNS server, which then send it back to the client resolver. 28

King Fahd University of Petroleum & Minerals Electrical Engineering Department EE 400, Experiment # 2

King Fahd University of Petroleum & Minerals Electrical Engineering Department EE 400, Experiment # 2 IP Addressing and Subnetting: Establishing Elementary Networks using Hubs, Switches and Routers. Objectives: